Class GrpclbState

grpclb/src/main/java/io/grpc/grpclb/GrpclbState.java:90–1281

The states of a GRPCLB working session of GrpclbLoadBalancer. Created when GrpclbLoadBalancer switches to GRPCLB mode. Closed and discarded when GrpclbLoadBalancer switches away from GRPCLB mode.

 * switches away from GRPCLB mode.
 */
@NotThreadSafe
final class GrpclbState {
  static final long FALLBACK_TIMEOUT_MS = TimeUnit.SECONDS.toMillis(10);
  private static final Attributes LB_PROVIDED_BACKEND_ATTRS =
      Attributes.newBuilder().set(GrpclbConstants.ATTR_LB_PROVIDED_BACKEND, true).build();

  // Temporary workaround to reduce log spam for a grpclb server that incessantly sends updates
  // Tracked by b/198440401
  static final boolean SHOULD_LOG_SERVER_LISTS =
      Boolean.parseBoolean(System.getProperty("io.grpc.grpclb.LogServerLists", "true"));

  @VisibleForTesting
  static final PickResult DROP_PICK_RESULT =
      PickResult.withDrop(Status.UNAVAILABLE.withDescription("Dropped as requested by balancer"));
  @VisibleForTesting
  static final Status NO_AVAILABLE_BACKENDS_STATUS =
      Status.UNAVAILABLE.withDescription("LoadBalancer responded without any backends");
  @VisibleForTesting
  static final Status BALANCER_TIMEOUT_STATUS =
      Status.UNAVAILABLE.withDescription("Timeout waiting for remote balancer");
  @VisibleForTesting
  static final Status BALANCER_REQUESTED_FALLBACK_STATUS =
      Status.UNAVAILABLE.withDescription("Fallback requested by balancer");
  @VisibleForTesting
  static final Status NO_FALLBACK_BACKENDS_STATUS =
      Status.UNAVAILABLE.withDescription("Unable to fallback, no fallback addresses found");
  // This error status should never be propagated to RPC failures, as "no backend or balancer
  // addresses found" should be directly handled as a name resolution error. So in cases of no
  // balancer address, fallback should never fail.
  private static final Status NO_LB_ADDRESS_PROVIDED_STATUS =
      Status.UNAVAILABLE.withDescription("No balancer address found");


  @VisibleForTesting
  static final RoundRobinEntry BUFFER_ENTRY = new RoundRobinEntry() {
      @Override
      public PickResult picked(PickSubchannelArgs args) {
        return PickResult.withNoResult();
      }

      @Override
      public String toString() {
        return "BUFFER_ENTRY";
      }
    };
  @VisibleForTesting
  static final String NO_USE_AUTHORITY_SUFFIX = "-notIntendedToBeUsed";

  enum Mode {
    ROUND_ROBIN,
    PICK_FIRST,
  }

  private final String serviceName;
  private final long fallbackTimeoutMs;
  private final Helper helper;
  private final Context context;
  private final SynchronizationContext syncContext;